用Cat-CVD方法制备多晶硅薄膜及结构分析  

Polysilicon Thin Films Obtained by Catalytic Chemical Vapor Deposition(Cat-CVD)Method and Structural Analysis

作　　者：张玉[1] 高博[1] 李世伟[2] 付国柱[1] 高文涛[1] 荆海[1] 

机构地区：[1]中国科学院长春光学精密机械与物理研究所北方液晶工程研究开发中心 [2]吉林彩晶数码高科显示器有限公司,吉林长春130033

出　　处：《液晶与显示》2006年第6期668-673,共6页Chinese Journal of Liquid Crystals and Displays

基　　金：国家自然科学基金资助项目(No.60576056)

摘　　要：以金属钨为催化热丝,采用热丝催化化学气相沉积,在300℃的玻璃衬底上沉积多晶硅薄膜。研究了H2稀释率、钨丝与衬底间的距离和反应室气体压力等沉积参数对制备多晶硅薄膜的影响,并通过XRD谱分析,确定了本实验系统的最佳多晶硅成膜条件:FR(SiH4)=5mL/min,FR(H2)=70mL/min,P=50Pa,L衬底与钨丝=7.5cm,T=30min,t衬底=300℃,特征峰在(111)面上。在接触式膜厚仪测量的基础上,计算出薄膜生长速率为0.6nm/s。对最佳成膜条件下制备的多晶硅薄膜进行刻蚀,形成不同的厚度,以便进行逐层分析。采用XRD和SEM方法对不同厚度的薄膜测试发现,随着薄膜厚度的减小,(111)面的XRD特征峰强度逐渐下降,(111)面上的晶粒尺寸基本没有变化,都是50nm左右。根据测试结果分析了薄膜的生长机制,提出了薄膜生长是分步成核,成核后沿(111)面纵向生长的观点。认为反应基元首先随机吸附在衬底上,在H原子的作用下在一些位置上成核,而在其他位置形成非晶相。已形成的晶核逐渐长大并沿(111)面纵向生长;已形成的非晶相也在生长,但上面不断有晶核形成。当薄膜达到一定厚度,非晶相表面完全被晶核占据,整个薄膜表面成为多晶相,此后整个薄膜处于沿(111)面的纵向生长阶段,直至反应结束,完整的晶粒结构呈柱状。Polysilicon thin films are deposited by catalytic chemical vapor deposition method. The substrate temperature is 300 ℃ and catalytic hot wire is tungsten filament. A systematic study of the effect of deposition parameter-hydrogen dilution ratio, substrate-to-filament distance and gas pressure on preparation of poly-Si film is presented. The optimal growth condition required for this material in this system is confirmed by analyzing XRD spectra of samples. It is as follows： FR（SiH4）= 5 mL/min, FR（H2）=70 mL/min, P=50 Pa, L衬底与钨丝=7.5 cm, T=30 min, t衬底 = 300 ℃, the characteristic peak is in the （111） direction. The growth rate calculated is 0.6 nm/s on the basis of the measure of the talystep profilometer. The optimal film is etched to form different thickness so that the analysis layer by layer is performed. It＇s found that the diffraction peak intensity in the （111） direction diminishes and the grain size doesn＇t change obviously they are all about 50 nm with the film thickness tested by XRD and SEM on the film with the different thickness. The film growth mechanism is analysed on the basis of the test results. The standpoint of the nucleation by step and then vertical growth along （111） direction is put forward. It＇s thought that the precursors firstly adsorb on the substrate and then the nucleation happens on some positions by the action of atom H while the amorphous fraction is formed on other positions. The formed nucleus grow up gradually along the （111） direction and at the same time the amorphous fractions grow up too but the nucleus form ceaselessly on the surface of it. When the film reaches the certain thickness, the surface of the amorphous fraction is held completely by the nucleus and the surface of the whole film is in the polycrystalline state. After this, the whole film grows along the （111） direction until the reaction finishes. The whole grain is in column.

关 键 词：多晶硅薄膜 催化化学气相沉积 沉积参数 逐层分析 分步成核 

分 类 号：O484[理学—固体物理]